Patent GB-933258-A (GB)
Title: Improvements in and relating to grinding machines
Inventor: FRIES JOHN ROBERT
IPC: B24B47/20
Filed: 1962-04-11
Abstract: 933,258. Grinding. LANDIS TOOL CO. April 11, 1962, No. 13982/62. Class 60. A grinding-machine comprises a grinding wheel 12 mounted on a support 11 movable toward and from a workpiece W, a feed mechanism for advancing and retracting the wheel support, manually-operable means 48 for actuating the feed mechanism, power means 56 for advancing and retracting the wheel support to grind the workpiece to a predetermined dimension, and means 60 permanently and operably connected to the manually operable means to register any workpiece dimension within the range of the feed mechanism, the registering means being initially adjustable with the feed mechanism set for a known dimension to show the known dimension when the power means is in its retracted position. The manually-operable means consists of a hand wheel 48 on a shaft 47 formed with a worm 46 engaging a pinion 45 on a shaft 40 which is located in the support 11 and has at its lower end a gear 41 engaged in a thread 42 in a shaft 25 in the machine base 10. The thread 42 acts as a rack so that rotation of the shaft 40 effects movement of the support 11 on the base 10. The shaft 25 is connected by gearing to a pawl-and-ratchet mechanism 35, 31 which is operated by a piston-and-cylinder device 36, 37 to rotate the shaft 25 and provide a fine feed or a movement to compensate for the wear of the grinding wheel. The shaft 47 is connected by gearing 70, 72, shaft 73 and bevel gearing 74, 75 to an indicator 60, and is also connected by a clutch 84, 85 to a slave 80 carrying a pinion 50 engaging a rack 55 which is movable up to a stop by an hydraulic motor 56 to rotate the shaft 40 and effect a feeding movement of the grinding wheel. In operation, the grinding wheel is first advanced to its forward position either by a rapid feed motor axially moving the shaft 25 or by the motor 56 moving the rack 55 until the rack engages its stop. The clutch 83, 84 is then disconnected and the grinding wheel advanced to a truing position by the hand wheel 48, the truing position being determined by a gauge 105, Fig. 6, having a surface 102 for engaging a reference surface on a footstock 101 and a surface 104 for positioning the truing tool 100. After the truing operation, the clutch 84, 85 is re-engaged and the grinding wheel retracted to its rearmost position. In that position the indicator is set to read the dimension corresponding to the size which the workpiece would be ground to when the grinding wheel is in its forward position wherein it was trued. As the grinding wheel reduces in size due to wear, the pawl-and-ratchet mechanism 31, 35 is operated at the end of each feeding movement by the motor 56 moving the rack 35 against its stop to rotate the shaft 25. To set the machine to grind a workpiece of a different size, the grinding wheel support is retracted by the hand wheel 48 which is then disconnected from the rack 55 by disengaging the clutch 84, 85. The hand wheel is turned until the required size of the workpiece is shown on the indicator, the clutch then being re-engaged so that the motor 56 can drive the rack up to its stop to advance the grinding wheel which grinds the work to the previously indicated size. For high precision grinding, the indicator is set so that when the rack engages its stop and the grinding wheel is in its foremost position, the workpiece is a small amount, say 0.001 inch, over size, the final size being reached by operation of the pawl-and-ratchet mechanism and indicated by a size indicator or gauging device. The grinding machine may be of the type used for grinding cylindrical or flat workpiece. The workpiece may be ground between opposed grinding discs. U.S.A. Specification 2,657,505 is referred to.